Acoustic skeleton chamber for string instruments



G. VlRZl Nov. 22, 1949 ACOUSTIC SKELETON CHAMBER FOR STRING INSTRUMENTSFiled June 28, 1946 ATTORNEY Patented Nov. 22, 1949 UNITED STATES PATENTOFFICE ACOUSTIC SKELETON CHAMBER FOR STRING INSTRUMENTS Giuseppe Virzi,New York, N. Y.

Application June 28, 1946, Serial No. 680,243

4 Claims. 1

This invention relates to musical string instruments.

One object of the invention is to provide an improved acoustic skeletonchamber for string instruments.

Another object of the invention is the provision of a musical stringinstrument having improved means for resiliently reenforcing a soundingboard or chamber thereof for free vibration in response to sound.

Another object of the invention is to furnish improved means forreenforcing a sound chamber of a violin or the like at the bridge and atthe sound openings.

Another object of the invention is to provide improved reenforcing meansfor a musical string instrument including an improved sound post for thebridge thereof.

Heretofore, the art as exemplified by violins and similar stringinstruments, has long been troubled by defects arising with frequentuse, ageing and occasional abuse of the instrument, especially the soundchamber thereof; cracks in the wood, and opening of a seam or jointwould develop, and Warping of the wood frequently occurred even infairly expensive violins. Sometimes any one of these conditions wouldcause other weaknesses to develop, as the sound chamber of a violin is ahighly coherent unit, in which the parts balance in respect to strainsand stresses. Having been engaged for many years in the repair ofviolins, I perceived the need for an innovation in the art, whilepreserving the essential, well known character of the violin. Marginalreenforcement was inadequate, and I found that the reenforcement had toextend into or over the delicately vibrating walls of the sound chamber,without interfering with the tonal quality of the instrument. I alsofound that undue rigidity of the sound post is undesirable where it isdesired to obtain superior distribution of stresses as in myskeletonized sound chamber.

It is therefore an object of the invention to provide improved means foraccomplishing the advantages referred to.

Other objects and advantages of the invention will become apparent asthe specification proceeds.

With the aforesaid objects in view, the invention comprises the novelfeatures, combinations and arrangements of parts hereinafter describedin their preferred embodiments, pointed out in the subjoined claims, andillustrated in the annexed drawing wherein like parts are designated bythe same reference characters throughout the several views.

In the drawing:

Figure 1 is a plan view of an acoustic skeleton chamber for a stringinstrument such as a violin, embodying the invention.

Fig. 2 is a horizontal sectional view thereof showing the bottom wall.

Figs. 3, 4, 5, and 6 are sectional views taken respectively on lines 33,4-4, 55, and 66 of Fig. 1.

Fig. 7 is a sectional view taken on the broken line l-'! of Fig. 1.

The advantages of the invention as here outlined are best realized whenall of its features and instrumentalities are combined, but usefulembodiments may be produced involving less than the whole.

It will be obvious to those skilled in the art to which the inventionappertains, that the same may be incorporated in several differentconstructions. The accompanying drawing therefore, is submitted merelyas showing a preferred exemplification of the invention.

Referring in detail to the drawing, in denotes a device such as asounding board or chamber for musical string instruments, exemplified ina sound chamber of a violin, from which certain conventional portionshave been omitted for clarity in the drawing. This device includes a topwall I I, a bottom wall I 2, and a side wall comprising the sections !3and I4 and the re-entrant portions l5. These Walls may be interconnectedin the usual manner adhesively or otherwise, and along the joints theremay extend the usual beadlike strips l6 of triangular cross section forreenforcing the joints between the walls. The front and rear walls I land I2 may be downwardly convexed, and in the front wall II there may beprovided the conventional S-shaped sound openings l7 between which islocated the bridge l8 for supporting the strings. Internally of thesound chamber Hi there is provided a sound post 2% hereinafterdescribed, located adjacent to one side of the bridge l8, and adjacentto the opposite side of the latter there is a conventional bass bar 2!which forms no part of the invention and is therefore indicated indotted lines. As above described, the chamber It may represent the soundbox of any well-known violin or other portable musical instrument,except that the sound post 20 in the particular construction thereof isa novel feature of the invention. The sound chamber is made of afinegrade of wood, with the grain running preferably lengthwise of theelongated front and rear walls H and I2 as respectively indicated at 22,23.

Reenforcing means is provided for the sound board or top wall I Icomprising one or more strips 25 of a suitable stiffening materialconsisting preferably of wood whose fine grain extends generallylongitudinally of the strip elements, the grain being indicated at 26.Each of these elements may be interrupted by the sound openings H toprovide cooperating strips 21. These strip elements preferably extendsubstantially through out the length of the top wall up to the adjacentmarginal walls as indicated at 28, 29, the bead l6 being interrupted toaccommodate the ends of these strips. Each strip element 25, 21 islongitudinally substantially curved for longitudinal elasticity orresilience. Preferably such curvature is of generally S-shape, thestrips intersecting each other at 30 so as to form a generally X- shapedreenforcement for the upper portion of the top wall and passing thencetoward opposite sides of the bridge I8 and diverging from each other atthe lower portion of the top wall. This arrangement has been carefullydesigned with a view to obtaining the best possible stress distribution.Where the strips are interrupted by the openings l1, reliance is placedupon the elements 2|], 2| for supporting the adjacent portion of the topwall. The strips may vary in mass or cross-section so that the sections21 thereof may be slightly heavier than those shown at 25 or they may beuniform in cross-section throughout. The mass of the strips is so smallas not to interfere with the sound vibrating quality of the top wall.For example, the cross section of each of these strips may be such thatits dimensions may be substantially equal or only slightly greater thanthe thickness of the top wall. These strips are caused to conform to theconvexity of the top wall and are preferably continuously securedthereto, adhesively or otherwise in a perfectly secure manner. Becausethe grain of the strips extends generally lengthwise thereof, theypossess ample strength and because the strips extend obliquely to thegrain of the top wall, they are adapted to afi'ord ample reenforcementat the critical sections of the top wall.

The bottom wall |2 indicates a sounding board provided with reenforcingmeans comprising elongated transverse strips 3|, 32 having angular edgesat 33, 34 and curved or concave edges at 35, 36, the strips consist ofwood with the grain running generally lengthwise thereof, as indicatedat 31, 38. These strips may terminate at the beads l6 or the latter maybe cut away so that the strips come into direct reenforcing engagementwith the walls l3 and IS. The strip 3| extends across the violin chamberadjacent to the upper portion thereof, and the strip 32 is locatedclosely adjacent to the sound post 20. These strips 3 32 are securedandfunction in a manner generally similar to the strips 25, 21. Inconstruc tion the strips 3|, 32 differ from the strips 25, 21principally in that they have substantially greater width and lessangularity or curvature, and thus exercise a substantially greaterreenforcing ef feet in a direction crosswise of the wall |2 to whichthey are continuously bonded, with the grain being approximately atright angles to the grain of the wall I2. It will be perceived that thestrips 3|, 32 act adjacent to the re-entrant walls |2 where substantialreenforcement is necessary, and the strip 32 is adjacent to the soundpost 20 to assist in taking up the stresses created thereby.

Extending generally lengthwise of the bottom wall |2 there aresupplemental reenforcing means in the nature of strips, one comprisingthe portions 4|), 4|, and the other portions 42, 43, these stripsconverging downwardly with the portions 4|, 43 intersecting at 44 andthence diverging at 45. These longitudinal forms may or may not extendthrough the adjacent portions of the bead l6 and they may increase inwidth as shown, although in thickness they may be substantially equal tothe strips 25, 21 and 3 32, and the grain thereof extendslongitudinally. It is noted that the portions such as 4|], 4| extend tothe strip 3| and are interrupted by th strip 32. These longitudinalstrip formations are continuously bonded to the wall H and they havesufiicient longitudinal curvature for resilience lengthwise thereof.They are in other respects similar in function to the strips 25, 21,and. cooperate therewith to assist the sound chamber in taking up thetension caused by the strings of the musical instrument.

It is thus seen that there is provided an acoustic skeleton chamber fora string instrument embodying a novel principle for increasing the lifeand durability of the sound chamber, and avoiding efiects due to warpingand unusual stresses to which the same may be subjected accidentally orotherwise, the several features of reenforcement operating at criticalpoints so as to cooperate with each other to avoid weakening of thesound chamber at any one point which might thereby result in thecreation of undue stress at some other point however remote. Byconstructing the reenforcing elements according to angular or curvedformations they possess sufficient longitudinal elasticity to permitfree vibration of the sound chamber. Because the strips are narrow andsmall in mass they will not exercise a dampening effect upon the soundvibrations. By suitable arrangement of the grain of the wood, thereenforcement is at a maximum, whereas the added mass of material isrelatively a minimum. It will be appreciated that additionalreenforcemerits may be added of varying size and shape and variouslylocated to meet the requirements of a particular sounding board orchamber, those herein illustrated representing basic needs for theinstrument.

The sound post 20 includes an angular or curved portion 5%} forlongitudinal resilience and is particularly characterized in that thegrain 5| of the wood extends obliquely or at an angle of approximately45 to attain the requisite strength and use of the resilient sound post,the various reen-' forcing strips for the walls II and it! may be madeof much smaller mass than otherwise. Nevertheless the sound post 20 hassuiiicient stiffness not only for adequately supporting the bridge, butto prevent possible setting and permanent deformation of the soundchamber under the pressure exerted by the musical strings.

It will be understood that the reenforcements herein mentioned, or thesound chamber as a whole, may be made not only of wood, but of any othermaterial, such as a plastic, which may be of fibrous or laminated natureto correspond in general to the grain of wood. Additional cornerreenforcements such as strips 55 may be employed, or the element 32enlarged to integrally include the strips 55, with the latter secured tothe rear Wall l2 in the manner hereinabove described. It will also beappreciated that a plurality of sound posts corresponding in principleto that shown at 20 may be employed.

I claim:

1. A musical string instrument having a wooden vibratory sounding boardhaving the grain thereof extending substantially lengthwise andresponsive to sound waves generated by strings, and reinforcinglongitudinally curved wooden vibratory strip elements spaced from theperiphcry of the board along a substantial length thereof and secured incontact with said board, said strips being disposed to extend at anangle to the grain of the board with ends of the element terminating atthe periphery of said board.

2. A musical string instrument having a sound chamber comprising woodenvibratory walls interconnected at an angle to each other and responsiveto sound vibrations generated by strings, reinforcing means includingbead-like strips extending along the periphery of the walls forreinforcing joints between adjoining walls, and elongated spaced Woodenstrip elements adhesively united to one of said walls, said elementsalong a substantial length of each being spaced from the periphery ofsaid first wall and directly connected at an end thereof to the other ofsaid angularly disposed adjoining walls, said bead strips being cut awayto permit said element end connection.

3. A musical string instrument having a sound chamber comprising woodenvibratory walls interconnected at an angle to each other and responsiveto sound vibrations generated by strings,

iii

and reinforcing means including spaced elongated wooden strip elementshaving the grain extending substantially the length thereof andadhesively united to one wall, said elements alon a substantial lengththereof each being spaced from the periphery of said first wall andhaving the ends thereof directly connected to the other angularlydisposed adjoining wall, said elements being longitudinally curved forresilience and disposed in symmetrical relation with each other and tothe contour of said first wall.

4. A musical string instrument having oppositely positioned soundvibrating walls responsive to sound generated by strings and a bass-barextending longitudinally along one of said Walls, and reinforcing meansfor said one wall including elongated strip elements adhesively unitedto said one wall in spaced relation to the periphery thereof, saidelements being longitudinally curved for resilience and having athickness less than one quarter that of the bass-bar so as to permit viration thereof with said one wall.

GIUSEPPE VIRZI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 109,696 White Nov. 29, 1870224,834 Marx Feb. 24, 1880 420,025 White Jan. 21, 1890 464,157 Hudson etal Dec. 1, 1891 673,949 Gould May 14, 1901 1,383,830 Leighton July 5,1921 FOREIGN PATENTS Number Country Date 53,303 Austria Apr. 25, 1912353,019 Germany May 10, 1922 633,516 France Nov. 9, 1928

